Radio communication systems are used for transmitting information, speech or data, with the aid of electromagnetic waves over a radio interface, also called an air interface, between a sending and a receiving radio terminal. Radio communication systems can be subdivided into a core network in which payload and signaling data of a plurality of terminals is transported over long distances on wires and via which a connection can be implemented to a fixed communication network, and into a Radio Access Network (RAN) via which the data received from the terminals is converted into a format suitable for the transmission in the core network and vice versa, the form of data received by the core network is adapted to radio transmission and forwarded to the relevant radio terminal, within the send area in which the terminal involved is located.
Radio communication systems of the first and second generation are currently in use around the world and, because of the great demand for mobile communication, are coming up against the limits of their capacity. The emerging capacity problems are to be resolved by the third-generation radio communication systems. One of the third-generation radio communication systems which shows the greatest promise of success is the Universal Mobile Telecommunication System (UMTS) that was specified by the standardization body 3GPP (Third Generation Partnership Project) (see for example: B. Walke, Mobilfunknetze und ihre Protokolle (Mobile radio networks and their protocols), Volume 1, P. 385-387, Teubner Verlag 2000).
Data is transmitted circuit switched in the UTRAN access network specified for UMTS in accordance with the ATM procedure. In this case the data which is to be transmitted over a connection is subdivided into ATM cells. The timing of ATM cells for a number of connections is interleaved and the cells are transmitted over the same physical connection. The connection channel in this case remains the same for the duration of the transmission. An overview of the ATM method is for example to be found in: B. Walke, Mobilfunknetze und ihre Protokolle (Mobile radio networks and their protocols), Volume 2, Chapter 8, Page 255 to 290, Teubner-Verlag 1998.
The demands on mobile communications are being paralleled by the increased demand for high bandwidth worldwide data communications. This data is communicated over the Internet according to the IP (Internet protocol) procedure. In this case data packets are transported over packet-oriented connections, i.e. connectionless, between the users. With packet-oriented transmission there is a free choice of connection channel between the users only for the transmission of the relevant data packet. A subsequent data packet can be routed via another channel. It is thus possible that the order in which the data packets are received differs from the order in which they were sent.
There is an increasing demand to be able to also transmit large volumes of data by mobile communication with a high bandwidth. An IP-based radio communication network has therefore been proposed (see for example: 3GPP, IP Transport in UTRAN Work Task Technical Report, in 3GPP TR 25.933 2001), in which connections are made using the IP procedure.